Mentored by Orange Prize winner Zadie Smith at the Iowa Writer’s Workshop where she studied in 2008, the judges thought Shipstead "showed great promise".

Pearson said: “The winner of the Dylan Thomas Prize before she’s 30, the smart money has to be on Maggie Shipstead winning a Pulitzer before she’s 50."

Seating Arrangements takes a satirical look at the pretentions of New England society, and is a study of an American family as it prepares for a wedding.

Matthews, said: “This was one of the hardest judging processes I’ve been involved in. Passions were running high because several of the books had such strong voices. However, Maggie shone as a truly accomplished writer whose effortless prose had great fluency and beauty.”

Pearson added: “At the age of 28, Maggie Shipstead has imagined herself inside the head of a 59-year-old male in thegrip of an erotic infatuation.

"This is territory that has been covered by the greats of American fiction, including John Updike and Jane Smiley. Maggie Shipstead doesn’t just follow in their footsteps; she beats a distinctive and dazzling path of her own. The world has found a remarkable, humane new voice to explain us to ourselves.”

Open to any published author in the English language under the age of 30, the award celebrates the legacy of Welsh poet and writer Dylan Thomas who wrote most of his best work in his 20s. This prize aims to recognise and support the literary heroes of the future.

Mr Florence said: “I've never known such an open field for a book prize. All the shortlisted books had advocates on the jury and had exceptional merits of different kinds. I am deeply grateful to my fellow jurors.

"If you have to be sequestered with a bunch of mates in a book club these are the guys to be with for insight, passion and elegantly expressed outrage.

"This prize celebrates the achievement of young writers, and does so in the name of the gabbiest, most compassionate, anguished and playful spirit of his age. The bar is set very high. We're confident that this year's winner honours that aspiration.”

The winner announcement is the climax of a week of events that four of the five shortlisted authors have participated in on behalf of the DylanEd programme.

Shipstead and her fellow shortlistees have visited schools and universities across Wales to give readings and participate in creative writing workshops in a bid to help inspire the next generation of young writers.

Shipstead joins previous winners Rachel Trezise for her set of short stories, Fresh Apples, which won the inaugural prize in 2006, Vietnamese writer Nam Le for The Boat (2008), Elyse Fenton for Clamour (2010), and the most recent winner, Lucy Caldwell for her novel, The Meeting Point (2011).